SOUTHERN FEBRUARY 2016 WHEAT SECTION 7 INSECT AND OTHER PEST CONTROL INTEGRATED PEST MANAGEMENT | LUCERNE FLEA (SMINTHURUS VIRIDIS) | EARTH MITES | SLUGS | APHIDS | ARMYWORM | SNAILS | SOIL PESTS | INSECT MONITORING TECHNIQUES FOR FIELD CROPS Table of Contents SECTION 7 WHEAT - Insect and other pest control Feedback February 2016 SECTION 7 Insect and other pest control Insects are not usually a major problem in winter wheat but sometimes they build up to an extent that control may be warranted. For current chemical control options, refer to the Pest Genie or Australian Pesticides and Veterinary Medical Authority (APVMA) websites. 1 Where chemical control is warranted, farmers are increasingly being strategic in their management and avoiding broad-spectrum insecticides where possible. Thresholds and potential economic damage are carefully considered. Agronomist’s view Insect and other arthropod pests that can pose a problem include blue oat mite (Penthaleus spp.), redlegged earth mite (Halotydeus destructor), Bryobia mites (Bryobia spp.), cutworms, aphids, slugs, snails, earwigs, millipedes, slaters, army worms, pasture webworm, pasture cockchafers, and grass anthelids, lucerne flea (Sminthurus viridis), leaf hoppers, slugs, snails, millipedes, slaters and locusts (Tables 1 and 2). Mice may also cause damage. Table 1: Pests that pose a risk to cereal crops 2 High risk Moderate risk Low risk Soil insects, slug and snails Some crop rotations increase the likelihood Information on pest numbers prior to sowing from Slugs and snails are rare on of soil insects: soil sampling, trapping and/or baiting will inform sandy soils management cereal sown into a long-term pasture phase Implementation of integrated slug management high stubble loads strategy (burning stubble, cultivation, baiting) above-average rainfall over summer–autumn where there is a history of slugs History of soil insects, slugs and snails Increased sowing rate to compensate for seedling loss caused by establishment pests Summer volunteers and Brassica weeds will increase slug and snail numbers Cold, wet establishment conditions expose crops to slugs and snails Earth mites Cereals adjacent to long-term pastures may Leaf curl mite populations (transmitters of Wheat Seed dressings provide some get mite movement into crop edges streak mosaic virus) can be increased by grazing protection, except under and mild wet summers extreme pest pressure Dry or cool, wet conditions that slow crop growth increase crop susceptibility to damage History of high mite pressure 1 DAF Qld (2012) Insect pest management in winter cereals. Department of Agriculture and Fisheries Queensland, http://www.daff.qld.gov.au/plants/field-crops-and-pastures/broadacre-field-crops/integrated- pest-management/ipm-information-by-crop/insect-pest-management-in-winter-cereals 2 NIPI. Winter cereals. NIPI IPM guidelines, http://ipmguidelinesforgrains.com.au/crops/winter-cereals/ Know more. Grow more. 1 Table of Contents SECTION 7 WHEAT - Insect and other pest control Feedback February 2016 High risk Moderate risk Low risk Aphids Higher rainfall areas where grass weeds Wet autumn and spring promote the growth of Low-rainfall areas—lower risk are present prior to sowing—higher risk of weed hosts; when weed hosts dry off, aphids of BYDV infection Barley yellow dwarf virus transmission by move into crops aphids High beneficial activity (not Planting into standing stubble can deter aphids effective for management of Wet summer and autumn promoting survival landing virus transmission) of aphids on weed and volunteer hosts Use of seed dressings can reduce levels of virus transmission and delay aphid colonisation Use of SPs and OPs to control establishment pests can kill beneficial insects and increase the likelihood of aphid survival Armyworm Large larvae present when the crop is at late High beneficial insect activity (particularly No armyworm present at ripening stage parasitoids) vegetative and grain-filling stages Rapid crop dry-down Table 2: Incidence of pests of winter cereals 3 Present, present in crop but generally not damaging; Damaging, crop susceptible to damage and loss; snails are More also a grain contaminant at harvest i information Crop stage cesar: Insect gallery Emergence Vegetative Flowering Grainfill NIPI: Insect Wireworms Damaging Present identification aids Cutworm Damaging GRDC Update Papers: Black headed cockchafer Damaging Present Don’t forget the good Earth mites Damaging Present guys—recognising and Slugs, snails Damaging identifying beneficial Brown wheat mite Damaging insects in your paddock Aphids Present Damaging Present Present cesar PestFacts: Grass Armyworm Present Present Damaging anthelids Helicoverpa armigera Damaging GRDC Ute Guides: Insects Stay informed about invertebrate pest threats throughout the winter growing season by GRDC Update subscribing to SARDI’s PestFacts South Australia and cesar’s PestFacts south eastern. Papers: Insect pests— resistance, virus vectors Subscribers to PestFacts also benefit from special access tocesar ’s extensive Insect and lessons from 2014 Gallery, which can be used to improve skills in identifying pest and beneficial insects. Use Tables 3 and 4 below to identify damage caused by key pests, and to assess risk and determine control measures for establishment pests. 3 NIPI (2014) Winter cereals. NIPI IPM guidelines, http://ipmguidelinesforgrains.com.au/crops/winter-cereals/ Know more. Grow more. 2 Table of Contents SECTION 7 WHEAT - Insect and other pest control Feedback February 2016 Table 3: Crop damage pest identification key for the Southern Region—cereals 4 Leaves or plants cut off and lying on the ground or protruding from small Webworm holes next to plants; brown caterpillars (up to 15 mm long) with black heads, present in web- lined tunnels; wheat or barley seeded into grassy pasture paddocks. Leaves or plants cut off and lying on the ground or protruding from small Pasture tunnel moth* holes next to plants. Slender larvae, up to 35 mm long, construct silk- lined tunnels that protrude above ground to form chimneys. Leaves or plants cut off and lying on the ground or protruding from small Grass anthelid* holes next to plants. Larvae are brown with black and yellow marking, covered in tufts of stout hairs and can grow up to 50 mm in length. Leaves of young seedlings fed upon or damaged; in severe cases Mandalotus weevil* seedlings are ring-barked at ground level causing them to drop. Adults are 3-5 mm long, round and dull brown resembling small clods of dirt. Plants eaten close to or below ground level causing plant death and bare Polyphrades weevil* patches within the crop. Larvae emerge from tunnels with rain events to feed on foliage. Can Blackheaded pasture cause bare patches in crops during late autumn and early winter. ‘C’ cockchafers* shaped larvae with six legs and a black to brown head capsule. Large portions of plants eaten and some leaves or plants cut off. Smooth, Cutworms fat caterpillars up to 40 mm long usually found just under the soil surface and may curl up when disturbed. Green material removed in irregular patches from one surface of the leaf Lucerne flea leaving white window-like areas; paddocks may appear white; presence of dumpy, wingless, greenish yellow insects, which spring off plants when disturbed. Leaves shredded or chewed, slimy trails. Slugs and snails Smooth, shiny brown animals with curved pincers at the end of the body. Earwigs Damage irregular, often similar to slug damage, mostly in patches, when sown in heavy stubble. Grasshoppers and locusts. Grasshoppers and locusts Minor leaf chewing; presence of dark brown to black caterpillars up to 60 Pasture day moth mm long with two yellow spots near posterior end. Presence of tiny 8-legged (nymphs have 6 legs) velvety black or brown Redlegged earth crawling creatures with orange-red legs, found on plants or on soil Mite Blue oat mite surface at the base of plants. Balaustium mite Plants stunted and dying at emergence and up to tillering; chewing of Spotted vegetable seed and stem below ground; white legless larvae up to 7 mm long weevil or Desiantha present near point of attack. weevil Plants stunted or dying; roots eaten; slow-moving, soft bodied insects Cockchafers African usually in a ‘C’ shape, cream-coloured apart from head and visible gut black beetle contents; found near roots. Plants yellowing and withering; on light soils mostly on coastal plain; Sandgropers** stems underground shredded; presence of elongated, cylindrical insects up to 75 mm long, first pair of legs adapted for digging. Green and straw-coloured insect droppings like miniature square hay Armyworm bales on ground; cereal heads on ground; some chewing of leaves and seed heads of weeds such as ryegrass. Smooth, fat caterpillars up to 40 mm long, with three stripes on collar behind head; found at base of plants or climbing plants. Seeds chewed but heads not severed; caterpillars up to 40 mm long, Native budworm and sparsely covered with small bumps and bristles, may be various shades related species of green, yellow, orange or brown; found on seed heads. Presence of many grey- green insects approx. 2 mm long, with or without Aphids wings, on upper portions of stem. If heavy infestations, plants stunted; sticky with secretions, possibly black mould growing on secretions; Damage in fine pale dots in wriggly or zigzag lines. Yellow to green, 3 mm Leafhoppers long wedge-shaped sucking insects that jump sideways when disturbed. * Relevant in S.E. Australia only 4 GRDC (2012) I spy. Insects of Southern Australian Broadacre Farming Systems Identification Manual and Education Resource. GRDC, http://grdc.com.au/Resources/Bookshop/2012/11/I-SPY Know more. Grow more. 3 Table of Contents SECTION 7 WHEAT - Insect and other pest control Feedback February 2016 Table 4: Establishment pests of the Southern Region—risk assessment and management 5 Pre-season Pre-sowing Emergence Crop establishment Earth mites and lucerne flea Assess risk. High risk when: If high risk: Monitor susceptible crops As the crop grows, • use an insecticide seed through to establishment it becomes less • history of high mite pressure dressing on susceptible crops using direct visual searches.